Effects of knee compartment, concomitant surgery and smoking on medium-term outcome of microfracture

Purpose: The aim of this study was to determine the effect of compartment location, concomitant arthroscopic surgery and smoking on the medium-term outcome of knee microfracture.

Methods: From a database of all 396 patients treated with microfracture for cartilage lesions in our Unit, details were taken of the 316 patients who met our inclusion criteria. Outcome was assessed by a self-administered postal questionnaire containing a general satisfaction question and a battery of four functional assessment scores. The rank sum of the four assessment scores was used as a single global functional outcome.

Results: After two rounds of questionnaires 196 patients responded. Their average follow up was 37 months. In all, 72% of the patients were satisfied with their outcome and 19% were not. Patients with an affected lateral or patellofemoral compartment improved 1.5 SD, significantly more than those with an affected medial compartment who improved 1 SD. However, their satisfaction rates did not differ significantly. Having concomitant knee surgery did not significantly affect the functional outcome or satisfaction rate. Significantly fewer smokers than non-smokers were satisfied (54 vs 76%) and more dissatisfied (34 vs 15%), but differences in functional outcome were small and non-significant.

Conclusions: Patients with a lesion in the patellofemoral or lateral compartment have a significantly larger improvement than those with a medial compartment lesion. Satisfaction rates among these patients groups are however similar. Having concomitant arthroscopic knee surgery, in particular partial meniscectomies and ACL reconstruction, hardly affects the outcome of microfracture. Smoking is associated with a lower satisfaction rate although it has only a small effect on functional outcome. Finally, younger patients fare better than older patients although a cut-off point is hard to define. This information should help surgeons counsel patients better regarding prognosis and expectations after surgery.